long-term memory systems of the human brain

Current knowledge is summarized about long-term memory systems of the human brain, with memory systems defined as specific neural networks that support specific mnemonic processes. In the late 19th Century, German Psychologist Hermann Ebbinghaus established that humans tend to forget most of what they learn in a class within thirty days. Without some aid to help us retain what we learn, massive amounts of crucial information are lost. This paper describes about the how to improve our memory, how repetition improves the efficiency of memory processing, by improving physical well-being how it helps improving memory, and ways to increase our depths of level of memory processing.

Introduction

In psychology, memoryÂ is regulated by a constantly changing organization of consciousness or an organism's ability to store, retain, and subsequently retrieve information. It has been hypothesized that three processes occur in remembering: perception and registering of a stimulus, temporary maintenance of the perception, or short-term memory; and lasting storage of the perception, or long-term memory.

Two major recognized types of long-term cognitive memory are:

Procedural memory-involving the recall of learned skills.

Declarative memory-the remembrance of specific stimuli. For long-term memory to occur there must be a period of information consolidation.

A conscious awareness in remember that they are recollecting something of the past. Some of what we experience day to day is stored away in our minds for future reference, but much of it is not. For example, you might describe in vivid detail the interior of a quaint ice cream parlor you visited last summer, but be unable to recall what flavor ice cream you had. On closer reflection, this is only the tip of the iceberg when we look at the full range of human memory capabilities. One of the interesting features of your memory system is that you don't control what is stored because much of our memory is submerged from conscious view.

Memory is an integral part of our existence, yet it is only vaguely understood. When you want to remember something doesn't mean that you can remember the entire. Indeed, when you thinking, most of what you thinking is not stuff that you consciously try to store. You didn't try to commit the whole thing that you did to your memory. In this regard, you might be unable to remember a complete of the event.

It's hard to grasp just how specific, or narrow of your thoughts and your memories. For example, suppose you passing your neighbor's house, you encounter a barking dog. There are several aspects of the dog that you could think about. Perhaps you could think about the sound of the dog's bark, what the dog looked like, or the meaning of the bark like why it's barking, whether it's barking at you, the possible that a barking dog will bite, and so on. Each of these thoughts will lead you to different memories of the event the next day. If you think about the sound of the dog's bark, the next day you'll probably remember that quite well, but not its appearance.

To put this example into broader terms, even simple concepts have multiple aspects of meaning, which one of these you think about will determine what you remember.

Literature Review

Ways to Improve Memory

There are 16 ways to improve our memory. The ways included convince ourselves that we do have a good memory that will improve, exercise your brain, exercise daily, reduce stress, eat well and eat right, take better pictures, give yourself time to form a memory, create vivid and memorable images, repeat things you need to learn, group things you need to remember, organize your life, try meditation, sleep well, build your memorization arsenal, venture out and learn from mistake and listening to binaural beats. (Ben Rubenstein, Theresa Mulligan & Tom Viren, 2010)

In the article "Improving Your Memory-Tips and Technique for Memory Enhancement" (Ellen Jaffe-Gill, M.A., Amara Rose, Gina Kemp, M.A., and Suzanne Barston, 2007), they suggested the stages of memory foundation and maintenance. The stages are acquisition, consolidation and retrieval. Besides that, they stated the tips for memory improvements. They suggested that brain exercises can improve memory because memory is just like a muscular strength, the more we work out our brain, and the better we will be able to process and remember information. Furthermore, they also stated the general guidelines and mnemonic devices to improve memory. Healthy habits and nutrition also suggested by them to improve our memory.

In "Human Memory: What It is and How to Improve It" suggested that there are many ways to improve our memory such as the use of certain mental technique, special care with nutrition and medicines (Silvia Helena Cardoso, 1997). For example, stimulate memory with using it to the utmost and challenge a novelty. Pay attention, concentrate and avoid all other thoughts can help us to improve our memory. Other ways which can improve our memory is relax, sleep and nutrition. Besides that, medication, alcohol, smoking and caffeine are believed that may interfere the memory function. Studies have shown that, when compared with non-smokers, individuals smokers of one or more packs of cigarettes a day had difficulties of remembering people's faces and names in a test of visual and verbal memory (Turkington, 1996).

We tend to forget things much easier as we age because the neurons in our brain responsible for memory lose elasticity over time. However, he suggested some methods to maintain a great memory for as long as possible. Sleep well is one of the methods he had suggested. Besides that, use acronyms and other mnemonic devices also help to improve our memory. Rest and eat brain "super foods" also suggested by him to improve our memory. (Todd ,2007)

There are 7 mnemonic devices to improve our memory. First, pegword method that is useful for memorizing lists of unrelated items in order with create a visual image of each item in the list with a "peg" word. Second, method of loci which is useful for memorizing lists of unrelated items in order with commits a "mental walk" to memory. Third, use acronym method which creates an acronym using the first letter of each of the items. Fourth, use the acrostic method which creates a sentence in which the first letter of each provides a cue for the materials. Fifth, music or rhymes method can be use to set a familiar tune, rhythm or rhyme on the materials that we going to memorize. Sixth, mnemonic association is the method which associated to-be-remember materials with an aspect of the material that is hard to remember. Lastly, the keyword method can be use for foreign vocabulary words. (Daniel T. Willingham, 2009)

Almost everyone would like to improve their memory. The temporal lobes of the brain are located behind the eyes and under the temples at the sides of head. The temporal lobes of the brain are associated with short-term memory and transferring memories to long-term storage. In addition, the temporal lobes are involved with language, reading social cues, understanding music and tone of voice, and mood stability. The hippocampus is another part of the brain located closer to the center and next to the temporal lobes. The hippocampus stores new information for several weeks and helps a person learn new skills. Omega-3 fatty acids and antioxidants are important in improving our memory. (Wendy Hodsdon, ND, 2006)

A multitude of molecular, cellular, systems and behavioral findings have demonstrated the need for sleep after learning for the consolidation of memory. (Seung-Schik Yoo, Peter T Hu, Ninad Gujar, Ferenc A Jolesz and Matthew P Walker, 2007)

Short-term memory

Short-term memory-closely related to "working" memory-is the very short time that you keep something in mind before either dismissing it or transferring it to long-term memory. Short-term memory is shorter than you might think, lasting less than a minute. It's what allows you to remember the first half of a sentence you hear or read long enough to make sense of the end of the sentence. But in order to store that sentence (or thought, fact, idea, word, impression, sight, or whatever else) for longer than a minute or so, it has to be transferred to long-term memory.

Short term memory (STM) is a limited capacity store that, for example, can be assessed with a digit span task. Most people can hold between five and nine items in STM, but by 'chunking' items together can hold more information. Without rehearsal, this memory trace fades over the course of minutes. A current debate is about how much of this is due to decay alone or interference from subsequent stimuli. Recall for items often shows a J-shaped 'serial position curve' where early and late items presented in a list are recalled better. Late item success is known as the recency effect and reflects short term memory fading, while early item success is known as the primacy effect and is tough to reflect a long term store (Matlin, 1996).

Short-term memory allows one to recall something from several seconds to as long as a minute without rehearsal. Short-term memory is believed to rely mostly on an acoustic code for storing information, and to a lesser extent a visual code. Conrad (1964) found that test subjects had more difficulty recalling collections of words that were acoustically similar (e.g. dog, hog, fog, bog, log).

This is the process whereby we can take advantage of prior knowledge to package information more effectively and hence to enhance storage and retrieval. For example, sequence of digits that comprised a number of familiar dates, such as 1492 1776 1945, would be easier to recall then the same 12 digits in random order.

However, short-term memory has been an unexplainable phenomenon with certain individuals "gifted" to remember large amounts of information, quickly, and be able to recall that information in seconds. Short-term memory is supported by transient patterns of neuronal communication, dependent on regions of the frontal lobeÂ (especially dorsolateral prefrontal cortex) and the parietal lobe.

The limited information which manages to pass the hurdle of selective filtering is not necessarily retained with any degree of permanence. It is placed in a temporary storage unit, where information is held just long enough for it to be analyzed and transferred to long term memory. Information received is held only for about five to twenty seconds, and if it is not attended to, either decays or is lost (Magill, 2001).

Part of the process of registering the information in the STM is to transform or encode it so it is capable of being rehearsed or practiced and later stored. Emphasis should be on rehearsing the information. It is here that the learner understands the meaning, message, intent, value and the representation of the information in relationship to other information in the memory. In motor skill learning, it is important that coaches and teachers should take into account the capacity of the STM. If a lot of information of a particular skill is given at any one time, then it is impossible for most students to remember all the instructions. So instructions are best kept brief, or broken down into parts to the degree that attention is properly maintained.

As we grow older with many cognitive conditions, our short-term memory span often becomes even shorter. This makes us more likely to have trouble keeping up with certain tasks, such as remembering which button to push in a bank's phone menu. It also gives our brains less time to successfully move new information to long-term memory, which makes us more likely to forget details of recent events, such as a story our children tell us or instructions our doctors give us.

Long-Term Memory

Long-term memory, or LTM, is the storehouse for information that must be kept for long periods of time. But LTM is not just a more durable version of STM; the stage model of memory suggests it's a different kind of memory altogether.

The storage in sensory memory and short-term memory generally have a strictly limited capacity and duration, which means that information is available only for a certain period of time, but is not retained indefinitely. By contrast, long-term memory can store much larger quantities of information for potentially unlimited duration. Its capacity is immeasurably large.

Long-term memories, on the other hand, are maintained by more stable and permanent changes in neural connections widely spread throughout the brain. The hippocampus is essential (for learning new information) to the consolidation of information from short-term to long-term memory, although it does not seem to store information itself.

Without the hippocampus, new memories are unable to be stored into long-term memory, and there will be a very short attention span. Furthermore, it may be involved in changing neural connections for a period of three months or more after the initial learning.

Types of Long-Term Memory

Tulving (1987) has proposed the existence of three kinds of long-term memory stage, each with distinctly different properties, and each probably based on different brain mechanisms.

The three type of Long-term memory:

Procedural Memory

-Memory for motor movement and skills

-Knowledge about how to do something

Semantic Memory

-Memory for meaning without reference to the time and place of learning

-Memories that recall a personal moment from our past

Episodic Memory

-Knowledge about the world

-Memory for specific experiences that can be defined in terms of time and space

-Stores as facts that make little or no reference to one's personal experiences

These various parts of long-term memory do not operate in isolation from one another. While it is not clear how they work together, it is clear that they are related and overlap. (Tulving,1972)

Storing Information for the Long-Term Memory

To store information over the long-term memory, you need to produce elaborate and distinctive memory records. Focusing on the meaning of the input, relating to be remembered information to other things in memory, and forming visual images of the input all lead to distinctive memory records. Forming a visual image is particularly effective, and many memory aids, or mnemonic devices, are based on the use of imagery. Long-term memory also depends on how information is actually presented:

Item presented near the beginning and end of a sequence are remembered well, are as items that have been repeated. Spaced or distributed practice turns out to be more effective than massed practice.

Two major problems related to the use of long-term memory:

To transfer the information accurately to long-term memory.

To retrieve the information accurately. The primary strategy for transferring information from working memory into long-term memory is referred to as encoding or elaboration.

These terms refer to the process of relating information to other information that is already stored in long-term memory. Piaget and other constructivists have developed detailed theories regarding how information is stored in long-term memory.

Differences between LTM and STM in four major ways:

The way in which information is recalled:

The amount of information stored in LTM is so vast, we cannot scan the entire contents of LTM when we looking for a bit of information, as we do in STM. Instead, LTM has to be indexed. We retrieve information from LTM using cues, much as we use a call number to locate a book in the library. This retrieval can be an intentional act or an unintentional one, as when hearing a particular song brings back memories of a lost love. In either case, only information relevant to the cue is retrieved, rather than the entire contents of LTM.

The form in which information is stored in memory:

LTM differs from STM in the kind of information that is most easily stored. You will recall that information is usually stored in STM in terms of the physical qualities of the experience (what we saw, did, tasted, touched, or heard), with a special emphasis on acoustic codes. Although sensory memories can be stored in LTM, information is stored in LTM primarily in terms of its meaning, or semantic codes.

The reasons that forgetting occurs:

Unlike STM, where information that is not rehearsed or processed appears to drop out the system, information stored in LTM is not just durable but actually appears to be permanent. Not all psychologists agree that memories in LTM are permanent, but there is a great deal of evidence supporting this view. If memories in LTM are indeed permanent, this means that "forgetting" occurs in LTM not because the memory is erased buy because we \are unable to retrieve in for some reason.

The physical location of these functions in the brain:

STM is primarily a function of the frontal lobes of the cerebral cortex, whereas information that is stored in LTM is first integrated in the hippocampus and then transferred to the areas of the cerebral cortex involved in language and perception for permanent storage.

Stages of Memory Foundation and Maintenance

There are 3 stages of memory foundation and maintenance: acquisition, consolidation, and retrieval.

At acquisition stage, new information enters our brain. The key to encoding information into our memory is concentration. Unless we focus on information intently, otherwise it goes "in one ear and out the other".

At second stage, that is consolidation, hippocampus sends a signal to store the information as long-term memory.

When we need to recall the information, we reach retrieval stage. Our brain have to activate the same pattern of nerve cells used to store it. The more frequently you need the information, the easier it is to retrieve it along healthy nerve cell connections (Ellen Jaffe-Gill, M.A., Amara Rose, Gina Kemp, M.A., and Suzanne Barston, 2007).

How To Improve Memory

A) Sleep Well

Everyone in the world needs consistently 7-8 sleeping hours to increase our memory. While sleeping, the brain disconnects from the senses, proceeds to revising and storing memory. Besides that, the brain appears to firm up memories of newly acquired information during sleep. At day time, a quick nap can be the impetus for a solution to a problem you have been working (Todd, 2007). Sleep is necessary for memory consolidation. The amount of sleep will affect the brain's ability to recall recently learned information. According to recent studies conducted at the Harvard Medical School, getting a good night's sleep may improve our short-term memory and long-term relational memory (Ben Rubenstein, Theresa Mulligan & Tom Viren, 2010). Insomnia would produce a chronic fatigue and would impair the ability of concentration and the storing of information (Silvia Helena Cardoso, PhD, 1997).

B) Nutrition

Eat well and eat right are very essential to improve our memory. Roughly 50-60% of the brain's overall weight is pure fat, which is used as insulation for its billions of nerve cells.Â The better insulated a cell, the faster it sends messages and the speedier our thinking.Â Therefore eating foods with a healthy mix of fats is essential for long-term memory.Â Fish, especially wild salmon, mackerel and anchovies, and dark leafy green vegetables are excellent choices (Todd, 2007)

B vitamins, especially B6, B12 and folic acid are good for our memory. These vitamins protect neurons by breaking down an amino acid, homocysteine, which is toxic to nerve cells. These vitamins also involved in making red blood cells, which carry oxygen. The best sources of B vitamins is spinach and other dark leafy greens, broccoli, asparagus, strawberries, melons, black beans and other legumes, citrus fruits and soybeans (Ellen Jaffe-Gill, M.A., Amara Rose, Gina Kemp, M.A., and Suzanne Barston, 2007).

Besides that, antioxidants like vitamins C, vitamins E and carotene are also essential in improve our memory. Antioxidants fight free radicals which are highly reactive and can damage cells that can occur with age. Antioxidants interact with them safely and neutralize them. Antioxidants also improve the flow of oxygen through the body and brain (Ellen Jaffe-Gill, M.A., Amara Rose, Gina Kemp, M.A., and Suzanne Barston, 2007). Eating many colors of fruits and vegetables ensures a wide variety of antioxidants to nourish and protect the brain. The best sources of antioxidants are blueberries and other berries, sweet potatoes, red tomatoes, spinach, broccoli, green tea, nuts and seeds, citrus fruits, liver (Wendy Hodsdon, ND, 2006).

Furthermore, Omega-3 fatty acids are a major component of the gray matter of the brain and can also improve brain activity. They count as "healthy" fats, as opposed to saturated fats and trans fats, omega-3 fatty acids protecting against inflammation and high cholesterol (Ellen Jaffe-Gill, M.A., Amara Rose, Gina Kemp, M.A., and Suzanne Barston, 2007). The fat in the brain is essential to proper nerve function, in nerve membranes, and as a component of brain synapses. People who eat diets high in saturated fats or trans-fatty acids frequently will show signs of dementia earlier than people who eat fish regularly. Omega-3 fatty acids can found in wild-caught, deep sea fish like wild salmon, tuna, mackerel and herring. Fish oil supplement is good for the brain and memory (Wendy Hodsdon, ND, 2006).

Moreover, water is also an essential source for our memory. Water help maintain the memory systems working, especially in older persons. According to Dr. Trukington, lack of water in the body has an immediate and deep effect on memory, dehydration can generate confusion and other thought difficulties (Silvia Helena Cardoso, PhD, 1997).

C) Brain Exercise

Memory, like muscular strength, is a "use it or lose it" proposition. The more we work out our brain, the better we will be able to process and remember the information. Regularly "exercising" the brain keeps it growing and spurs the development of new nerve connections that can help improve memory (Ellen Jaffe-Gill, M.A., Amara Rose, Gina Kemp, M.A., and Suzanne Barston, 2007).

By developing new mental skills we can keep our brain active and improve its physiological functioning. The mental skills can be puzzles and games like crossword and Sudoku which can practice on for several minutes per day. Novelty and sensory stimulation are the foundation of brain exercise. We can use our memory to the utmost and challenge a novelty and they can be fun. "Almost any silly suggestion can work," says David Eagleman, PhD, neuroscientist and assistant professor at Baylor College of Medicine in Houston, Texas. For example, if you work in an office, learn to dance. If you are a dancer, learn to deal with a computer. This could stimulate your brain's neural circuits to grow. Besides that, we can try a "neurabic" exercise, which is an aerobic exercise for our brain. This will force us to use your faculties in unusual ways, like showering and getting dressedÂ with our eyes closed, take a course in a subject we don't know much about, learn a new game of strategy, cook up some recipes in an unfamiliar cuisine, drive home via a different route, brush teeth with opposite hand. That's the most effective way to keep your synapses firing (Ben Rubenstein, Theresa Mulligan & Tom Viren, 2010).

D ( i) Repetition Priming

Definition: the 'repetition effect': a repeated stimulus is processed better on the second occurrence than on the first. (Christophe Pallier , Nuria SebastiÂ´an-GallÂ´es and Angels ColomÂ´e, 1999)

Repeated process of a stimulus often facilitates performance on a cognitive task. This facilitation is known as repetition priming and, because it can arise in the absence of conscious recollection of the original stimulus presentation, is often assumed to reveal an implicit form of memory. Repetition priming is a very reliable phenomenon and has been observed in numerous tasks - for example, lexical decision (Scarborough, Cortese, and Scarborough, 1977) and word-fragment completion (Tulving, Schacter, & Stark, 1982)

The basic effect reported in numerous masked repetition priming studies is that manipulating the similarity of a briefly presented, pattern masked ''prime'' word and an immediately following and clearly visible ''target'' word produces systematic differences in target reaction time (RT; greater overlap = faster RTs). Such effects have typically been interpreted as reflecting processing that is started by the masked prime and then modified when the ensuing target is similar to or different from the prime along some dimension of interest (e.g., orthographic, lexical, or semantic). Because subjects are usually unaware of the identity of the prime, it is widely believed that this type of priming is predominantly sensitive to the fast feed-forward (automatic) components of word recognition (Forster, Mohan, & Hector, 2003; Lamme, Zipsser, & Spekreijse, 2002).

D (ii) Repetitive Learning

quantities from repetition. Advertising is a primary example of this phenomenon - with companies spending billions of dollars to present us with seemingly mind-numbing repeated messages. These messages work, even though they are basically passive. Repetition is even more effective when it is an active process and if repetition has "meaningful results, then learning will take place." (Jarrett Thoms, 2001)

"Many studies have demonstrated strong positive effects of repetition on learning. Repeated presentation of items increases memory for those items (Cyndi McDaniel, 2003). Repeated retrieval is also reported to improve memory." By repeating important concepts and then forcing the learner to retrieve those concepts several times, you strengthen the neural pathways, making subsequent retrieval easier and retention more durable and long-lasting. "In us, memories do not naturally sit still in cold storage." (John Sutton, 2004)

As repeated stimulus is processed better on the second occurrence than on the first, this shows that working memory can be reinforced via repetition, for example, students who practice more in mathematics will have a better chance to solve mathematical question easily when a similar question came out.

E) Mnemonic devices

Mnemonics are clues of any kind that help us remember something, usually by causing us to associate the information we want to remember with a visual image, a sentence, or a word. (Daniel T. Willingham, 2009)

Peg-word system. Peg-word system is a method which is useful for memorizing list of unrelated items in order as well as the specific numbers associated with the words. The key to success in using the peg system is visual association. We can create a visual image of each item in the list with "peg" word. The pegs provide cues to memory. This method using bizarre imagery helps to ensure that the cues are distinctive and unlikely to be confused with other cues. For example, pegs which is rhyme with numbers, "one is a bun, two is a shoe, three is a tree, four is a door, five is a hive" and so on. Next, match these items with the list of words we want to remember. It becomes a task similar to the imagery activity in which we had to remember word pairs using visualization. For example: If we have to write an entry in your journal for school, we also have a geometry assignment due tomorrow, we also have to read a chapter from our psychology text book. We could use either a mental image of our textbook, or an image that represents the topic in history that we are studying. Let's say we also had to walk the dog. Perhaps "leash" would be a good keyword." Then, we also have to remember to feed the dog - dog bowl. We also plan to eat supper with our friends - perhaps a plate or the dining room table would be good for this. We don't want to forget to brush our teeth after dinner. After dinner, you put your pajamas on, drink a glass of water, and go to sleep. We can use the peg system to track our schedule. (Daniel T. Willingham, 2009)

bun + journal

shoe + geometry shapes

tree + history book

door + leash

hive + dog bowl

sticks + plate

heaven + toothbrush

gate + pajamas

vine + water

hen + sleep

Method of loci. This method also useful for memorizing lists of unrelated items in order. We can commit a "mental walk" to memory that is a familiar route with separate and identifiable locations, and then create a visual image that associates each item on the list with a location on the mental walk. In order to use the method of Loci, we must first imagine a place with which we are familiar. There are several possible places we could use. We must be able to identify several locations within that one place. It is best if these locations can be given a logical order, such as clockwise, or top to bottom. As with the peg-word strategy, method of loci using bizarre imagery helps to ensure that the cues are distinctive and unlikely to be confused with other cues. For example, here's a mental walk from my front door to my driveway. The first location is my front porch, which has a bird's nest by the door, the second is the sidewalk, which has a large crack, and the third is my asphalt driveway with a red paint stain. To memorize the list onion, duck, artist, I would associate onion with my front door, perhaps by putting onions in the nest instead of eggs. Then I'd associate duck with the sidewalk by imagining the duck with its beak stuck in the crack, and artist with an artist admiring the paint stain on the asphalt. (Daniel T. Willingham, 2009)

Acronym and Acrostic. Create an acronym using the first letter of the items that we have to remember, if we can remember the acronym, we have a good cue for the items. For example, the planets, in order of their distance from the sun: Mecurey, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. We can memorize using acronym method: MVEMJSUNP = My Very Earnest Mother Just Served Us Nine Pickles. The colors of the rainbow, in order: Red, Orange, Yellow, Green, Blue, Indigo, Violet. The acronym method used to memorize is ROY G. BIV (A made-up name). (Daniel T. Willingham, 2009)

Music or Rhymes. The item that we have to remember is set to a familiar tune, set to a rhythm, or made into a rhyme. Rhymes are easier to remember because they can be stored by acoustic coding (a type of short term memory coding in which us remember information by the way it sounds). Music and rhymes are always use among young children as in learning alphabet with ABC song. If we forget the words, the melody can provide a cue to help us remember it. (Daniel T. Willingham, 2009)

Keyword. This method is often used for foreign vocabulary words. When we would like to learn foreign language, we can find a word from any language we are familiar with and that is close in sound to the foreign vocabulary word. Then, create a visual image that connects the sound-alike word to the translation of the foreign word. For example, the Spanish word for mushroom is "champiñones". It is sound like the English word "champion". Create a visual image of a boxing champion in the ring, arms aloft in victory, wearing big mushrooms on his hands instead of gloves (Daniel T. Willingham, 2009)

Conclusion

Memory is often associated with the "thinking of again" or "recalling to the mind" of something learned at an earlier time. Memory has separated into 2 terms that are short-term memory and long-term memory. The short term memory is some of the information in sensory memory is then transferred to short-term memory and allows one to recall something from several seconds to as long as a minute without rehearsal. However, long-term memory is the storage in sensory memory and short-term memory generally has a strictly limited capacity and duration, which means that information is available for a certain period of time, but is not retained indefinitely.

Otherwise, the best way to improve memory seems to be to increase the supply of oxygen to the brain, which may be accomplished with aerobic exercises; walking for three hours each week suffices, as does swimming or bicycle riding. One study found that eating frequently such as five small meals a day promotes a healthy memory by preventing dips in blood glucose, the primary energy source for the brain.